Seat spring unit

ABSTRACT

A seat spring unit mounted on horizontally spaced frame rails and consisting of upper and lower connected spring members. The upper spring member forms the primary load support section for the spring unit and includes a return bent upon itself section at its rear end which is supported on the lower spring member. This construction thus adapts the spring unit for supporting light loads wherein the entire resistance to the load is taken up by the upper spring member, the return bent section of which provides increased comfort for the seat occupant in the occupant&#39;&#39;s tail bone area where principal support is necessary for comfort. When heavier loads are applied to the spring unit, the lower spring member provides additional resilient resistance to load after the upper spring member has been deflected, thus enabling construction of seating units capable of comfortably supporting occupants whose weights vary over a wide range.

[ Feb. 29, 1972 [54] SEAT SPRING UNIT [72] Inventors: Harold l. McMahon,High Point, N.C.;

Albin J. Niewulis, Lexington, Ky. [73] Asnignce: Hoover Ball and BearingCompany, Saline.

Mich.

[221 Filed: Jan. 27, 1970 [2!] Appl. No.: 6,256

52 us. Cl ..267/107 [51 1 Int. Cl ..A47c 23/ 16 [58} Field ofSearch..267/107, 108, 109, 1 i0, 111

[56] References Cited UNITED STATES PATENTS 3,361,423 1/1968 Gniech eta1 ..267/107 2,591,185 4/1952 Neely ..267/107 X Primary Examiner-ArthurL. La Point Attorney-Olsen and Stephenson [5 7] ABSTRACT A seat springunit mounted on horizontally spaced frame rails and consisting of upperand lower connected spring members. The upper spring member forms theprimary load support sec tion for the spring unit and includes a returnbent upon itself section at its rear end which is supported on the lowerspring member. This construction thus adapts the spring unit forsupporting light loads wherein the entire resistance to the load istaken up by the upper spring member, the return bent section of whichprovides increased comfort for the scat occupant in the occupants tailbone area where principal support is necessary for comfort. When heavierloads are applied to the spring unit, the lower spring member providesadditional resilient resistance to load after the upper spring memberhas been deflected, thus enabling construction of seating units capableof comfortably supporting occupants whose weights vary over a widerange.

6 Claims, 4 Drawing Figures Patented Feb. 29, 1972 2 Sheets-Sheet 1 NINVENTORS HAROLD l. lMc MAHON ALBIN J. N'IEWULIS flaw ATTORNEYS SEATSPRING UNI'll This invention relates generally to springs for seatingstructures and more particularly to an improved spring unit capable ofproviding improved seat occupant comfort and having loading resistingcharacteristics which vary over a wide range.

In seating structures of the type to which this invention re lates, suchas furniture chairs and sofas, the principal area of the spring unitwhich affects the comfort of the seat occupant is the area of the springunit adjacent the back cushion in the seating structure. This portion ofthe spring unit supports what is commonly referred to as the tail bonearea of the seat occupant which is the area of the occupant throughwhich the principal seating loads are transmitted to the spring unit. Itis desirable to provide a spring unit which is capable of resilientlyyielding to the tail bone load without bottoming out in response totheapplication of heavy tail bone loads. The principal objective of thepresent invention, therefore, is to provide a spring unit capable ofproviding a tail bore support which will quickly yield under load and toprovide cooperating primary and secondary load-supporting sections inthe spring which can yieldably resist heavier loads.

The spring unit of this invention consists of a pair of upper and lowerconnected spring members, each of which includes a plurality of torsionbars. The upper spring member is formed at its rear end with a returnbent upon itself section so that it has a downwardly and forwardlyinclined portion that extends under the main load-supporting portion.The downwardly and forwardly inclined portion terminates in a foot whichis supported on and connected to the lower spring member, and as aresult, when a seating load is applied to the upper spring member, therear end portion readily deflects so as to resiliently drop away fromthe seat occupant to thereby provide the desired seating comfort. Thelower spring member includes a main section and upwardly inclined endsections which are mounted on the usual frame rails so as to locate theload-supporting portion of the upper spring member at the desiredelevation relative to the frame rails. As a consequence, when a', heavyload is applied to the spring unit, the upper spring member is allowedto continue its deflection by deflec tion of the lower spring member tothus accord the desired seating comfort without danger of the springunit bottoming out so as to give the feeling of unyielding support.

Further objects, features and advantages of this invention will becomeapparent from a consideration of the following description, the appendedclaims, and the accompanying drawing in which:

FIG. I is a perspective view of one embodiment of the spring unit ofthis invention,

FIG. 2 is a side elevational view of the spring unit of FIG. I, shown.mounted on a pair of frame rails, and showing the spring unit in anunloaded condition;

FIG. 3 is a side elevational view of the spring unit of FIG. 1,illustrated similarly to FIG. 2, showing the deflected position of thespring unit when subjected to a relatively light seating load; and

FIG. 4 is a side elevational view, illustrated similarly to FIGS. 2 and3, of the spring unit of FIG. 1, showing the spring unit in a deflectedposition caused by the support of a heavy load thereon.

With reference to the drawing, the spring unit of this invention,indicated generally at lit), is illustrated in FIGS. 1 and 2 asincluding an upper spring member 12 and a lower spring member I4 whichare vertically spaced and are connected in a manner hereinafterdescribed. The unit I is illustrated in FIG. 2 in an unloaded conditionmounted on a seating structure frame which includes a front rail 16 anda rear rail 18. The lower spring unit 14 has a main section 20 formed atits front end with an upwardly and forwardly inclined portion 22 and atits rear end with an upwardly and rearwardly inclined portion 24. Thefront end portion 22 terminates in a horizontally extending foot 26formed with a prong 28 inserted in an opening 30 in the frame rail 16.The foot 26 includes torsion bars which function for a purpose to behereinafter described. Similarly, the rear portion 24 terminates in afoot 34 provided with a prong 36 extended into an opening 38 in the rearframe rail 13. Intermediate its ends, the main section 20 the lowerspring member 14 has torsion bars lower 40 which function for a purposeto be hereinafter described.

The upper spring member 12 includes a main load-supporting section 42having a pair of torsion bars 44 at its front end which are secured byconventional clips 46 to the torsion bars 32 in the lower spring memberM- so as to mount the front end of the upper spring member 12 on thelower spring member 14. The rear end of the main load-supporting section4l2 of the upper spring member 12 is return bent upon itself, bytwisting a rear end torsion bar 48 so as to provide a downwardly andforwardly inclined rear end portion 50 which extends under theload-supporting section 42. The inclined section 50 terminates in a foot52 which is parallel to the main section 20 of the lower spring member14. The foot 52 includes a pair of torsion bars 54 which are parallel toand disposed in a side-byside relation with the torsion bars 40 in thelower spring member 14. Conventional clips 56 are employed to connectthe side-byside torsion bars 40 and 54 so as to mount the rear end ofthe upper spring member 12 on the lower spring member 14.

In the operation of the spring unit 10, assume that a seating load, themajor portion of which is located substantially as indicated by thearrow L in FIG. 2, is applied to the unit 10. For seating comfortpurposes, it is desirable that the unit it) readily drop away from theload L to give the feeling to the seat occupant of resilient support inthe tail bone area, namely, the area of the occupant located adjacentthe rear frame rail 18. The return bent upon itself construction of theupper spring member 12 provides this result, as illustrated in FIG. 3,which shows how the upper spring member 12 readily deflects in adownwardly concave form so as to yieldably resist the load. In otherwords, the section 42 of the spring 12 functions as a primaryload-supporting section which readily deflects toward the inclined endportion 50 without causing substantial deflection of the lower springmember 14. However, when the magnitude of the load L causing the primarydeflection illustrated in FIG. 3 is increased, the main section 26) ofthe lower spring member 114 is capable of functioning as a secondaryload-sup porting section so that it will likewise deflect to thedownwardly concave form illustrated in FIG. 4. Thus, the spring unit 10is capable of yieldably resisting loads extending over a wide range ofmagnitudes. When light loads are applied to the spring unit 10, theprimary load-supporting section 42 resists the load and when the load isheavier, the spring section 20 cooperates with the section 42 to providethe necessary yieldable resistance to the load to impart comfort to theseat occupant. In all cases, the primary load-supporting section 42readily folds downwardly toward the inclined end section 50, since thetorsion bar 48 will readily twist, so as to quickly impart a feeling ofresilience to the seat occupant. It is to be un derstood that thisreturn bent upon itself construction at the rear end of the upper springmember I2 is readily adaptable to other forms of spring units within thepurview of this invention, for example, a spring unit in which both endsof the primary load-supporting section 42 would be provided withinwardly inclined end sections 50 which extend under the primaryload-supporting section 42.

We claim:

1 In a seating structure which includes a pair of frame rails, a springunit supported on and extending between said rails, said spring unithaving vertically spaced primary and secondary loadsupporting sections,each of said supporting sections including a plurality of connectedtorsion bars, said primary section having an end portion supported onand disposed above said secondary section, said end portion being returnbent upon itself so that it is inclined downwardly toward said secondarysection in a direction away from the adjacent frame rail, said endportion terminating in a plurality of torsion bars positioned adjacentto and connected to torsion bars in said secondary section the ends ofsaid secondary section being connected to said frame rails and a mainportion thereof being arranged in a supporting relation with said endportion of said primary section, said secondary section including anupwardly inclined end portion located between said primary end portionand said adjacent frame rail.

2. A seating structure according to claim 1 wherein said secondarysection includes a second upwardly extending end portion terminating ina foot supported on the other one of said frame rails, and wherein saidprimary section has a second end portion supported on said foot.

3. A spring unit comprising upper and lower vertically spaced springmembers, said upper spring member having a main load support section andbeing return bent downwardly upon itself at one end of said section soas to have an inclined portion extended under said load support section,said upper member being secured at its ends to said lower member, saidlower spring member having a main section engaged with said inclinedportion of said upper spring member and upwardly extending end sectionsone of which is adjacent to and spaced horizontally from said inclinedportion of said upper spring member.

4. A spring unit according to claim 3 wherein the other one of saidlower spring member end sections terminates in a foot, means securingone end of said upper spring member to said foot, and means securing theopposite end of said upper spring member to said lower spring membermain section adjacent to said one end section.

5. A spring unit according to claim 4 wherein said upper and lowerspring members include horizontally spaced torsion bars, the torsionbars at the ends of said upper spring member being engaged with disposedin a side-by-side relation with some of the torsion bars in said lowerspring member, and clip means securing said side-by-side torsion barstogether.

6. A spring unit according to claim 5 wherein said load-support sectionof said upper spring member and said main section of said lower springmember are substantially coextensive in length.

1. In a seating structure which includes a pair of frame rails, a springunit supported on and extending between said rails, said spring unithaving vertically spaced primary and secondary loadsupporting sections,each of said supporting sections including a plurality of connectedtorsion bars, said primary section having an end portion supported onand disposed above said secondary section, said end portion being returnbent upon itself so that it is inclined downwardly toward said secondarysection in a direction away from the adjacent frame rail, said endportion terminating in a plurality of torsion bars positioned adjacentto and connected to torsion bars in said secondary section the ends ofsaid secondary section being connected to said frame rails and a mainportion thereof being arranged in a supporting relation with said endportion of said primary section, said secondary section including anupwardly inclined end portion located between said primary end portionand said adjacent frame rail.
 2. A seating structure according to claim1 wherein said secondary section includes a second upwardly extendingend portion terminating in a foot supported on the other one of saidframe rails, and wherein said primary section has a second end portionsupported on said foot.
 3. A spring unit comprising upper and lowervertically spaced spring members, said upper spring member having a mainload support section and being return bent downwardly upon itself at oneend of said section so as to have an inclined portion extended undersaid load support section, said upper member being secured at its endsto said lower member, said lower spring member having a main sectionengaged with said inclined portion of said upper spring member andupwardly extending end sections one of which is adjacent to and spacedhorizontally from said inclined portion of said upper spring member. 4.A spring unit according to claim 3 wherein the other one of said lowerspring member end sections terminates in a foot, means securing one endof said upper spring member to said foot, and means securing theopposite end of said upper spring member to said lower spring membermain section adjacent to said one end section.
 5. A spring unitaccording to claim 4 wherein said upper and lower spring members includehorizontally spaced torsion bars, the torsion bars at the ends of saidupper spring member being engaged with disposed in a side-by-siderelation with some of the torsion bars in said lower spring member, andclip means securing said side-by-side torsion bars together.
 6. A springunit according to claim 5 wherein said load-support section of saidupper spring member and said main section of said lower spring memberare substantially coextensive in length.